Method of making paper tubes



Dec. 5, 1950 E. G. HENSLER METHOD OF MAKING PAPER TUBES Filed Nov. 23, 1946 FIG.

Fae. 4-

Patented Dec. 5, 1950 METHOD OF MAKING PAPER TUBES Elmer G. Hensler, Barton, Wis., assignor to McGraw Electric Company, a. corporation of Delaware Application November 23, 1946, Serial No. 711,988

1 Claim.

This invention relates to a method of makin paper conduits or tubes which are formed of wound paper pulp or other fibrous material.

In the manufacture of paper pulp tubes, such as conduits, it is the usual practice to wind the paper pulp on a mandrel until the desired thickness has been obtained, and then remove the tube from the mandrel. The removal of the wet and easily damaged tube from the mandrel requires a high degree of skill and the usual method was to blow air under pressure between the tube and mandrel at each end of the tube to cause it to expand suificiently so that it could be removed from the mandrel. It was a virtual impossibility to maintain a close tolerance for the internal diameter of the tube and it frequently happened that portions of the tube stuck to the mandrel and damaged the inner surface of the tube.

After the tubes were removed from the mandrels, they were dried. During this drying process the tubes frequently shrunk and often had internal voids as moisture vapor became trapped between the inner and outer surfaces of the tube due to the fact that the inner and outer surfaces dried first and produced a hard surface which greatly hampered, and sometimes prevented, the passage of moisture vapor from the interior of the wall of the tube. In addition to this, the tubes frequently warped during drying and had to be straightened. It was found that where a blast of air was employed to hasten drying, that the end of the tube against which the air was directed became frayed and had to be trimmed off.

Tubes produced in the manner hereinabove set forth had to be individually inspected for internal diameter, for straightness, and for damage to the inner surface. Such tubes as passed inspection were subsequently impregnated with a waterproofing and insulating material in the usual manner.

This invention is designed to overcome the above noted defects and to provide a process of making tubes which eliminates warping during drying or change in internal diameter, which guards against damage to the inner surface of the tube, which avoids the production of voids during drying, and which insures a straight tube with correct internal diameter and free from voids and free from fraying at the end, thus eliminating the necessity of individual inspection for internal diameter, for straightness, and for integrity of inner surface, and the necessity for trimming one'end.

- In general, this method of making paper tubes 'tape 1 prevents the greatly increases production, does not requirea high degree of skill of the operator, and results in a much more uniform product.

An embodiment of the invention is shown in the accompanying drawings, in which:

Figure 1 is a diagrammatic view of a portion of the machine for winding the paper tubes from paper pulp.

Figure '2 is a fragmentary detail of the first roller in the series on the machine.

Figure 3 is a fragmentary view showing a paper tube completely wound from pulp on a metal sleeve, such view being partly broken away and partly insection.

Figure 4 is a view corresponding to Figure 3 showing the sleeve with the paper tube thereon suspended and showing by means of arrows the direction of air flow.

Fig. 5 is a fragmentary view partly broken away and partly in section showing a portion of a drying room with tubes suspended therein.

In practicing the process forming the subject matter of this invention, the paper tubes are wound from the paper pulp which is indicated by the reference character I and which is maintained at a predetermined level within a suitable tank 2 in the usual manner. A screen roller 3 is partially submerged in the paper pulp and has a partial vacuum formed therein. It picks up the paper pulp and carries it to an upper roller i which is also provided with a screen and which has afelt covering. This upper roller has a vacuum formed internally thereof, which may be slightly higher than that in the roller 3 in accordance with the usual practice. The winding mandrel is indicated by the reference character 5. Ordinarily, the paper pulp in the old process would be wound on the mandrel, but in the process forming the subject matter of this invention, the mandrel removably carries a thin metal shell or sleeve 6 on which the paper pulp is wound. The details of the rollers or drums 3, t, and 5 are not shown as they are of the usual and Well known type.

Itis to benoted from Figure 2 that the screen roller 3 is provided with a tape l which extends completely around the roller adjacent one end and near one end of the screen 3. The narrow picking up of the paper pulp at the part covered by the tape and consequently the paper tube is wound in two sections, namely ashorter'section 9 and a main or longer section ID separated by a small space ll, approximately the width of the tape i,

- After the paper pulphas been wound to a suit pipes Hi to heat the air and withfans orany other suitable means IQ for producing a downward blast of such heated air. Any other suitable drying room could be employed.

The air rushing downwardly passes through the metal sleeve 6 and around the=paper tube, It'is' to be noted that the small section 9 of the paper tube acts as a shield to prevent the air from fraying or splitting apart the larger or main section ll) of the paper tube and thus acts as a guard member. The result of this is that when the tube is finally dried, there is no necessity for trimming the upper end of the tube. Heretofore the upper ends of the tubes were found to be frayed or split due to the downward draft of air and had to be trimmed off. During the drying process the temperature is maintained at a suitable point. For example, as merely as a matter of illustration, at 160 F; The drying continues until the paper tubes. are thoroughly dry.

It is to be noted that the metal. sleeves 6' ab-. sorb heat from the air much more quickly than thepaper tubes and consequently the drying of the paper tubes progresses from theinside outwardly and the outer surface of the paper tubes is maintained moist during drying due to the passage therethrough of the vaporized water or other liquid from the interior of the tube. Heretofore, where the tubes were simultaneously dried at substantially equal rates from the inside and outside, as for example when they were not provided with the metal sleeve, it was found that a hard surface was formed on the outside and on the inside of the tube prior to complete drying of the tube and that the trapped water vapor formed voids within the tube as it could not freely escape either from the inside or the outside. However, by following the method hereinabove outlined, the drying progresses from the inside to the outside and the water vapor freely escapes through the outside of the tube until the drying has been completed.

It is to be notedalso that the paper pulp tubes when placed within the dryer are extremely fragile and have no set or inherent rigidity. The metal sleeves-expand due to the heat, andshape the interior of the tubes. As drying progresses, the paper tubes acquire a set.

After drying has been completed, the metal sleeves with the dried paper tubes thereon are removed from the dryer and. are allowed to cool. During this cooling the metal sleeves shrink away from the paper tubes and free themselves from the paper tubes. They are then freely withdrawn from the paper tubes.

The small sections 9 are discardedandareused again in making. pulp. The upper; end; of each of the dried tubes requires no. trimming whatsoever; Also there is no: warping of these dried papertubes as the metal sleeves hold them pers fectly straight throughoutthe drying. operation. In addition to this, there isno damage to the interior: of: the paper; tubes; as. the; surface: of; the 15 interior of the paper tubes is never disturbed and is kept smooth and uniform throughout its extent by the metal sleeve during the drying process.

Further than this, the internal diameter of the tube is accurately maintained by the metal sleeve and, therefore, tubes manufactured in accordance with this process have a very much closer tolerance for internal diameter than tubes manufactured in the customary manner.

In actual practice, the metal sleeves are made quite thin and may be made of aluminum alloy or other suitable material. One aluminum alloy that has'been found very satisfactory has the following composition; .25% copper, .6% silicon,

1.% magnesium, .25% chromium, 97.9% aluminum-.-

It is to be understood that the data is given merely as an illustration and is not to be construed as limiting the invention in any sense. Any suitable metal sleeve may be employed if desired.

Wherever the expressions paper pulp or paper tube are employed, it is to be understood that these expressions are not limited strictly to paper pulp or paper tube but are intended to cover any fibrous pulp or fibrous tube.

In actual tests conducted, it has been found that a. very marked increase in production results from the process. Further it has been found that there is no blistering or damage to any portion of the tube and that inspection for straightness and internal diameter can be wholly ispensed with.

Althoughthe tape i has been shown adjacent one end only of the screen roller, it is nevertheless within the province of this invention to have a tape adjacent each end of the screen roller. The lower smaller section of the paper tube would not act, as a guard, as does the upper smaller section, but would eliminatethe necessity of trimming the lower end, the elimination of the necessity of; trimming the upperend being secured. by the use of the upper smaller section as hereinabove set forth.

Further than. this, no particular skill is required ofthe operator as in. the heretofore known processes.

It will be seen that a novelmethod of making paper tubes has been provided by-this invention which may be very expeditiously followed-and which results in a uniform,- prpduct free from warping, blistering or. variationsininternal diameter.

Although. this invention has been, described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied-and is to be interpreted, as claimed.

I claim:

The method of making paper tubes. comprising winding paper pulp on a metal sleeve in two secticns with one of the sections. relatively short axially of the metal sleeve and located adjacent one end of the metal sleeve, directing a blast of heated air towards that end. of the metal. sleeve having the relatively short section; of paper tube thereon, whereby the relatively short section, of paper tube acts as a shield and guards the. adjacent; end of the longer section of paper tube from fraying due to the blast of heated air, continuing the drying process until the paper tube is thoroughly dried and set and maintaining a fixed relation between the short and longer sections. of aid e ter tub h u hout. he en dryi 5 process, cooling the paper tube and metal sleeve, UNITED STATES PATENTS and withdrawing the metal sleeve from the paper Number Name Date tube- 539 777 Peters May 21 1895 ELMER HENSLER- 5 932,802 Merrill Aug. 31, 1902 1,040,437 Seigle Oct. 8, 1912 REFERENCES CITED 1,040,438 Seigle Oct. 8, 1912 The following references are of record in the 1,147,262 Parker July 20, 1915' file of this patent: 1,234,701 Parker July 24, 1917 1,730,629 Rule Oct. 8, 1929 

